Hi Sandy1664,
Please use code tags when posting code in the future.
A fork/join splits the current thread into multiple parallel child threads, one for each statement in the block. The parent thread suspends until all child threads complete or terminate. Your fork/join block contains two statements, so there will be two child threads spawned. Each statement happens to be a begin/end block, which will int turn execute each statement inside it sequentially. Your begin/end blocks contains one statement - a forever loop, which repeatedly executes its statement (another begin/end block) over and over indefinitely.
So your fork/join block will suspend the parent thread indefinitely until both forever loops are terminated either by a break or some other process terminating statement.